The present application pertains to the use of isosorbide ethers in detergent applications, and the use of the isosorbide ethers as thickener for aqueous compositions.
Isosorbide (or 1,4:3,6-dianhydrosorbitol, see formula below) is the anhydride of sorbitol:

Upon heating sorbitol for example with concentrated sulfuric or hydrochloric acid, two molecules of water are eliminated with the formation of isosorbide. So far, these compounds are also known generally as dianhydrohexitols (including besides isosorbide also the isomers isomannide and isoidide). Besides isosorbide, certain derivatives of isosorbide are well known, inter alia mono- and diesters, and ethers, in particular mono- and dimethylethers of isosorbide. Those ethers are known to have good solvent properties for pharmaceutical and cosmetic compositions. EP 186 276 A2 discloses C1-C4-Alkyldiethers of isosorbide useful in oral hygiene preparations. The document discloses both, symmetrical as well as unsymmetrical ethers. A process for the preparation of such ethers is disclosed in EP 315 334 A2, using dialkylcarbonates and a basic catalyst to etherify the isosorbide. Chatti et al. reported in Recent Res. Devel. Organic Chem., 7 (2003): 13-20 ISBN: 81-7895-093-6 a method to prepare various dialkylethers of isosorbide using microwave irradiation. Isosorbidethers are also known to be suitable in personal care applications, as disclosed in EP 1 216 685 A2.
As isosorbide is derived from natural sources, applicable by double dehydration of starch, it is an interesting basis to obtain new compounds based on renewable resources. In this field, there is a constant search for new derivatives with new properties to suit the needs in some applications areas.
Surface-active formulations such as, for example, manual dishwashing detergents or hair shampoos, liquid detergents or shower gels are more or less concentrated aqueous surfactant preparations that are all expected to have a viscosity which, on the one hand, is low enough to ensure problem-free handling by the user but which, on the other hand, is also high enough to allow economical use. For preparations which are actually marketed in their in-use concentration and which do not have to be diluted by the user at all before use, this means that the water-thin surfactant solutions have to be adjusted to a relatively high viscosity. In many cases, this is done by the addition of electrolyte salts or polymers. However, in critical cases, including for example anionic surfactants containing internal polar groups and, in particular, sugar surfactants of the alkyl glucoside type, this measure is unsuccessful. Thus, the viscosity of alkyl glucoside solutions, for example, can be distinctly reduced by addition of sodium chloride.